Flexible coupling between tail cone and jet pipe



April 13, 1954 w. BOYD ET AL FLEXIBLE COUPLING BETWEEN TAIL CONE AND JET PIPE 3 Sheets-Sheet l- Fild April 4, 1951 INVENTORS M BOYD ALTASHLEY M njoamsy April 13, 1954 w BOYD ET AL 2,674,844

FLEXIBLE COUPLING BETWEEN TA'IL CONE AND JET PIPE Filed April 4, 1951 3 Sheets-Sheet 2 IN VENTOHS 'PEII April 13, 1954 w. BOYD ET AL FLEXIBLE COUPLING BETWEEN TAIL CONE AND JET PIPE Filed April 4, 1951 5 Sheets-Sheet 3 I vs IIVVENTOHS M BDYD ILEPASH LE Y PE Patented Apr. 13, 1954 FLEXIBLE COUPLING BETWEEN TAIL CONE AND JET PIPE Winnett Boyd, Bobcaygeon, Ontario, and Arthur Edward Pashley, Toronto, Ontario, Canada, assignors to A. V. Roe Canada Limited, Malton, Ontario, Canada, a corporation Application April 4, 1951, Serial N 0. 219,148

11 Claims. 1

This invention pertains to improvements in the means of coupling the jet pipes to thetail cones of aircraft gas turbine engines.

To facilitate installation of a gas turbine enginein an aircraft, particularly when the engine is mounted in a nacelle in the wing, it has been found desirable to install the engine and its jet pipe separately in the airframe and then to make the joint between the jet pipe and the tail cone assembly of the engine as a subsequent operation.

, However as this procedure usually necessitates the provision of access doors in the nacelle -or other surrounding aircraft structure, it results in a heavy and complex structure and the discontinuities formed in the smooth surface by the access doors detract from aerodynamic efiiciency. Furthermore it has been standard practice in the past to couple the jet pipe to the tail cone assembly by fastening the jet pipe to the periphery of the outer casing of the tail cone assembly, thus producing a long and substantially rigid structure in which distortion under the applied thrust and temperature loading, and the iiexure of the airframe in fiight, are liable to introduce indeterminate stresses and perhaps even failure. H

The main object of this invention is to, provide a coupling between the tail cone and jet pipe which is flexibleand yet strong enough to withstand the loads imposed upon it by normal operation. Another object of the inventionis to provide between the aforesaid two components a coupling which can be readily assembled and disassembled. Other objects and advantages will become apparent during the course of the following description. 7 In the accompanying drawings forming a part of this application and in which like characters are used to designate like parts throughout the several views:

tached in accordance with this invention, various major components of the engine being generally indicated by dotted lines;

Figure 2 is a partially sectional view, on an.

still larger scale of the locking nut assembly and of a wrench for the assembly shown in Figure 4;

Figure 6 is a sectional view taken line 66 in Fig. 5; and

Figure '7 is a fragmentary sectional view of the peripheral seal shown in Figure 2 but on a still larger scale.

It will be seen from Figure 1 that a jet pipe iii is coupled to a tail cone assembly II, of a gas turbine engine I2. The purpose of the jet pipe is to conduct the exhaust gases from the turbine I3 of the engine to the outside of the aircraft. The jet pipe is normally cylindrical but not necessarily straight, since an irregular shape may be required to conform to the essential structural features of theaircraft in which it is installed.

The tail cone assembly II comprises an annular casing or outer member Ila and an inner member IIb, known as the tail bullet, which is substantially conical and which is supported in spaced relationship within the outer member I id to provide an annular space I4 through which the exhaust gases from the turbine are discharged. Cruciform struts I5 spanning the annular space I4 serve to support the tail bullet Within the assembly.

The main coupling ofthe jet pipe It to the tail cone assembly II is effected by a somewhat Iflexible tie rod I6 and a spider, generally indicated by reference numeral I'I,'situated within along the the upstream end of the jet pipe and secured to the apex of the tail bullet Ilb. A flexible gastight seal, generally indicated by reference numeral I9, is provided at the peripheral juncture of the outer member Ila of the tail cone and the jet pipe. I V r From the drawings, particularly from Figure 7,

' it will be seen that, aroundthe circumference,

enlarged scale, of part of the tail cone assembly and the jet pipe;

Figure 3,is a fragmentary sectionalview illustrating a modifiedcoupling between the jet pipe and the tail cone assembly;

Figure 4 is a fragmentarysectional view show- I ing still another coupling between the jet pipe and the tail cone; w

F e hi raem r ta yi eqtio a n w one the jet pipe Ii) is axially spacedfrom the outer member Ila of the tail cone but registers therewith by means of the aforementioned seal it. This seal includes a forwardly extending sleeve I9a mounted on the outer periphery of a thin annular diaphragm l9b which is attached at its inner periphery to the surface of the jet pipe. The sleeve I9a slides axially over a spigot flange I mountedat the downstream end of the outer member I la of the tail cone, leaving an annular space between the flange I90 and the diaphragm I91). This annular space is partiallyfilled with resilient insulating material I 9d between the diaphragm 19b and a rim Illa on the'upstream end of the. jet pipe I0. A locking device 20 for preventing relativerotation ofthe tail coneand jet ciably hotter than the sleeve 119a which is protected from the said gases by the insulating material 19d; in consequence the flange expands relatively to the sleeve and binds thereon to form a gas-tight joint. 'Ihe-sealis'fiexible by-virtue of the diaphragm 192).

There are several constructions by which the jet pipe may be removably attached to the tail cone by means of the rod iE-and. thevspider H. For example if the jet pipe is straight and coaxial with the tail cone throughout its length, the rod i6 may be integral with the spider ii as-is' shown in Figure 2.-The spider i'i com prises four support vanes i'ia which extend radially and slightly rearwardly (to accommodate thermal expansioniirom-the spider hub ill) to the walls of the jet pipe Hi, to which they are attached b,*setscrews- 2l;-the walls of the jet pipe are-*reinforcedlocally by *a' band 10b through which the aforesaid setscrews pass. From, the

" hub I-Ib the tie rod extends forwardly to the apexof the t'ailbullet I lb and carries at its for- Wardenda" male-thread 22; which is heavily silver-plated to-avoid-seizing--and which will register with "a f-emale thread '23 apically situated inthe tail-bullet'ythis registration is facilitated by the provision of a-pronounced lead on the male-thread: The coupling of the jet pipe to the tail cone, according to" this construction, is 'eiiected byfirst sliding the sleeve me over the flange i 90, thereby centering the jet pipe relative tothe tail-cone and guiding the threaded end of the red It intothtethreaded apex of the tail bullet-lib; and subsequentlyrotating the whole jet-pipe to screw the-rodhome. If the. downstream end of the jet pipeis supported inamanner which will prevent "rotation after assembly,

no further locking of *thecoupling to the tail cone is required; but onthe other hand,if the method of suspension is such as to-permit rotation, for example if th jet pipe is suspended in the'-aircra-ft by means of a plain circular hoop,

some locking device for-the coupling-must be provided.- In the co-nstructionillustrated in Figmes 2 and 7' this device takes the form of a single setscrewfifla which is inserted, after the coupling-operation, iii a bracket 2th mounted on the outer member i la of the tail cone; thesetscrew has an extension which is engageable with a forked lug 20c onthe sleeve 19a, thereby preventing furtherrelative rotation between the jet pipe and the tail cone. The setscrew 29a is itseh" locked against unscrewing by a wire 28d. In most installations it is. possible to locate this simple locking device so that it can bereached through an opening or access door provided primarily for some other purpose.

If the jet pipe is not straight, so that the coupling cannot be effected by rotating the pipe, the device shown in Figure 3 can be employed. In this construction a'female thread 23" at the apex of a tailbullet lib is carried in a nut 24 rotatably mounted ina bearing'25 and remotely actuated, from a point outside'the outer member i la of the tail cone, bya bevel gear-mechanism 25 led throughone of-the cruciform struts 15 by which the'tail bulletis-supported? The' nut 24 may be locked against rotation after assembly by a lock-plate 21 which is adapted to engage the hexagonal head 28 of the bevel gear mechanism and which is mounted on springs 29 so that it may be released automatically by the application of a wrench to the said head.

Figure 4 shows yet'another construction which may be used in installations requiring an irregularly shaped or oblique jet pipe. According to this construction the hublib" of a spider ii" is hollow and a rod iii" is attached as a permanent extension of a tail bullet 1 lb". The down- --stream'end of the rod is shouldered at 30 to engage the hub of the spider, and a partially threaded cylindrical extension 3! of the rod it passes through the hub. The said extension, which is shown more clearly in Figure 5, is hollow to accommodate a locking device, comprising a hollow plunger 32 and a spring 33 which urges the plunger outwardly in a downstream direction. The plunger is prevented from rotating relative to therod by arivet 3 3, which is fastened transversely in the rod and passes through a longitudinal slot 35 in the plunger, thereby permitting longitudinal displacement of the plunger while preventing rotation. As shown in Figures 5 and 6, the plunger has a crown St; which, when the plunger is at its full travel under the influence of the spring, is adapted to engage the internal serrations 31a of a special nut 31 threaded on the extensions 3 i. In this construction the coupling is efiectedin the same manner as previously described, xcept that in this instance the extension 3| of the rod it" is inserted into the hub of the spider II" and the special nut 37 is-rotated by a long-handled socket wrench 38 manipulated from the rear or'downstream end of the pipe. The wrench has a central protuberance 39 which serves to depress the plunger 32 againstthe spring 33 in'order to disengage the crown 36 from the serrations 31a during the tightening or removalof the nut.

Those skilled-in the art will recognise that the construction is particularly suitable for use in installations embodying reheat or afterburner equipment, wherein the components of the afterburner may be-mounted on the radiating support vanes of the spider ll. It will be readily-understood therefore that variations in the shape, size and arrangement of the detailed parts of the assemblymay be embodied without departing from the characteristic features of the invention.

cone; flexibleattaching means extending from the apex of the said inner member to the jet pipe to secure it to the tail cone, means manipulable from outside the tail cone and jet pipe for connecting the attaching means; and means between the adjacent peripheral edges of the jet pipe and the said outer member for sealing said edges andpositioning the pipe relative to said outer member.

2. In an aircraft, a gas turbine engine having a turbine and atailcone-through which the exhaust gases from the turbineare discharged, the

said taiT-coneha'ving an annular outer member I means; and flexible sealing ber supported a jet pipe in peripherally registering conduct the said exhaust gases from the tail cone; attaching means, including a flexible rod extending from the apex of the said inner member and means connecting the said flexible rod cone and jet pipe for connecting the attaching means between the adjacent peripheral edges of the jet pipe and the said outer member.

3. In an aircraft, a gas turbine engine having a turbine and a tail cone through which the the said tail cone having an annular outer member and a substantially conical inner memin spaced relationship within the outer member; ing relationship with the annular outer member 3 to conduct-the said exhaust gases from the tail cone to the within flexible of the attaching means to secure the jet pipe tail cone, comprising a spider secured the jet pipe and having a hub, and a said inner member, means manipulable from outside thetail cone and jet pipe for connecting the attaching means; and sealing means between-the adjacent peripheral edges of the jet pipe and the said outer member.

4. In an aircraft, a gas turbine engine having a turbine and a tail cone through which the exhaust gases from the turbine are discharged, the said tail cone having an annular outer member and a substantially conical inner member supported in spaced relationship within the outer member; a jet pipe in peripherally registering relationship with the annular outer member to conduct the said exhaust gases from the tail cone; attaching means to secure the jet pipe to the tail cone, comprising a spider secured within the jet pipe and having a hub, and a flexible rod connecting the said hub to the apex of the said inner member, means manipulable from outside the tail cone and jet pipe for connecting the attaching means; and means providing radial support and a substantially gas-tight seal between the adjacent peripheral edges of the jet pipe and the said outer member.

5. In an aircraft, a gas turbine engine having a turbine and a tail cone through which the exhaust gases from the turbine are discharged, the said tail cone having an annular outer member and a substantially conical inner member supported in spaced relationship within the outer member; a jet pipe arranged in peripherally registering relationship with the annular outer member to conduct the said exhaust gases from the tail cone; attaching means to secure the jet pipe to the tail cone member, comprising a spider secured within the jet pipe and having a hub, and a flexible rod connecting the said 'hub to the apex of the said inner member, means manipulable from outside the tail cone and jet pipe for connecting the attaching means; and an annular flexible diaphragm mounted externally on one of the jet pipe and the said outer member, a spigot flange mounted on the other of the jet pipe and the said outer member, and a sleeve carried on the outer periphery of the said diaphragm and slidably engaging the spigot flange.

6. In an aircraft, a gas turbine engine having a turbine and a tail cone through which the exhaust gases from the turbine are discharged, the

a jet pipe in peripherally registerrod connecting the said hub to the apex I and a substantially: conical inner =memberSsupported in spacedrelationship within the outer.

, member;

relationship with the annular outer member to said tail conehaving annular outer-member. and v a substantially conical inner member supported in spaced relationship withinthe outer member; a jet pipe in peripherally registering relationship with the annular outer member to conduct the .said exhaust gases from the tail cone; attaching means extending from the apex of the said'inner member to the jet pipe to secure it to the tail cone, means manipulable from outside the tail cone and jet pipe for. connecting the attaching means; and an annular. radial diaphragm externally mounted on theperiphery of the jet pipe, a spigot flange mounted on the engaging the spigot flange, and heat insulating exhaust gases from the turbine-are discharged, material between the sleeve and the jet pipe.

said outer member, a sleeve carried on the outer periphery of the said diaphragm and slidably -7. In an aircraft, 'a gas turbine enginehaving a turbine and a tailcone through, which the exhaust gases from the turbinev are discharged, the said tail cone having an annular outer member and a substantially conical inner member supported in spaced relationship within the outer cured within the jet pipe and havinga hub, a

flexible rod connecting the said hub to the apex of the said inner member, the said rod having a thread at one end, and one of the said hub and the said apex being threaded to engage the said thread of the rod; and means providing radial support and a substantially gas-tight seal between the adjacent peripheral edges of the jet pipe and the said outer member.

8. In an aircraft, a gas turbine engine having a turbine and a tail cone through which the exhaust gases from the turbine are discharged, the said tail cone having an annular outer member and a substantially conical inner member supported in spaced relationship with the outer member; a jet pipe arranged in peripherally registering relationship with the annular outer member to conduct the said exhaust gases from the tail cone; attaching means to secure the jet pipe to the tail cone, comprising a spider secured within the jet pipe and having a hub, a flexible rod attached at one end to the hub and threaded at the other end, the apex of the conical inner member being threaded to engage the said threaded other end of the rod; flexible sealing means between the adjacent peripheral edges of the jet pipe and the said outer member; and locking means to prevent rotation of the jet pipe relative to the tail cone.

9. In an aircraft, a gas turbine engine having a turbine and a tail cone through which the exhaust gases from the turbine are discharged, the said tail cone having an annular outer member and a substantially conical inner member supported in spaced relationship with the outer member; a jet pipe arranged in peripherally reg istering relationship with the annular outer member to conduct the said exhaust gases from the tail cone; attaching means to secure the jet pipe to the tail cone, comprising a spider secured within the jet pipe and having a hub, a flexible rod attached at one end to the hub and threaded at the other end, a rotatable threaded member at the apex of the said conical inner member, and rotatable means extending outside the said outer member and geared to the said rotatable threaded member for rotating the rotatable threaded :member to: engage'zthe: threaded; end

a of the :rod; and;flexiblesealingymeansi between the said outer: member.

' 10. In an airc1'aft, :a gas: turbine engine having a turbine and avtail cone-.throughawhich the exhaust; gases from the turbine are discharged, the said tail cone having an annular outer member and'a substantially ccnical'inner member supported in .spacedirelationship' with 1 theouter member; a jetpipe arranged in peripherallyregistering..relaticnship with the an- .gases from the tailbone; attachingmeans to a hub, a flexible 'rod' secured at one secure the jet pipe to the tail cone, comprising aspidersecured within the jetpipe and having end to. the

apex of the said'conical inner member of the tail cone and removably attached at the other 7 .end to the hub; and flexible sealing means be- A tween the adjacent peripheral edges of the jet pipe and the said outer member.

11. In an aircraft, a gas turbine engine having a turbine and a tail cone through which the exhaust gases from the turbine are discharged, the said tail cone having arr-annular outer member and a substantially conical inner member supported in spaced relationship with the outer I member; a jet pipe arranged in peripherally rega the-adjacent peripheral edges of; the jet pipe and -.pipe"to the tail: cone; comprising a spider secured withinlthe jet: pipe .andhaving a hub .with an 'i axialiboref-afiexib1e.;rod: secured at one:.end to ;member .to. conduct: the, said "exhaust. gases: from the tail cone :attaching means to; secure the jet :the .apex of the said .conicalinner, member of the tailcone and protruding at the other end through the axial bore of the hub, theprotruding nuhthreaded onthe protruding portion ofrod; andfiexiblesealing means betweentheadnular outer member to conduct'the saidexhaust portion of the .rod being threaded, and;ax lock the jacent peripheral edges of the jet-pipe and the said outer member.

iRei'erences'Cited in ,the file of this patent UNITED STATES PATENTS Number Name Date 1,639,225 .-.,Grace Aug. 16, 1927 2,494,659 'Huyton Jan. 17, 1950 2,510,506 Lindhagen et a1. :June 6, 1950 2,557,883 a Miller June 19, 1951 7 2,580,207 Whittle -Dec. 25,.1951 2,603,945 Brown 'Ju1y 22,-1952 FOREIGN PATENTS Number .Country 1 'Date 4' 19,915 GreattBritain 1'Jan. 13, 1949 

